Sorry I've not responded sooner, busy with remodeling a laundry room and kitchen.
I would pry the two hubs apart, take the spider out and count the legs, looks to be three. While the spider is out measure the thickness of the leg and the outside diameter of the spider and then match it up with a like spider from McMaster. If the spider is too far gone to get the O.D. just use the O.D. of the hub.
I don't see a need to go to a larger coupling, some engineer already put the proper sized one in the machine. How long have you had the machine, and how much do you use it? A year, two or more and if the coupling just took a dump now, I don't think that's too bad.
Oh, and the hubs don't look bad enough to be spending a bunch on replacing them.
My bad, just looked at the pictures on a larger screen and I see you can't "just pry the hubs apart".
I think you'll have to remove either the motor or the other shaft so you can measure and replace the spider.
Or get a precise measurement of each shaft diameter, rounded up or down to the nearest metric or fractional size, and key size then order a complete replacement coupling.
Last edited by Jerry Bruette; 05-19-2022 at 4:28 PM.
Reason: Added info
Confidence: The feeling you experience before you fully understand the situation